Blach Phosphate

[Richard P.]

Is black phosphate the same as Zinc Phosphate? I can find Zinc phosphate at Esatwood, but can't locate Black.

[Dick W.]

Re: Blach Phosphate

If you are doing it yourself, you will need to zinc plate (or copycad) the part first, and then use Caswell Plating's, or another vendors zinc blackener.

[Gene M.]

Re: Black Phosphate

Rich,
I use a phosphate solution that you drop the part into let set for a minute and done. Part must be bare steel, real clean and it comes out dark, dark gray close to black. But not black. Perfect for c3 hood latches. The piece needs to be oil wiped to cure. It is ok but is not good for a car you are going to drive (will rust), trailer queen is ok.

My friend has done some small parts for me in a similar manor and they are quite black. Same oil wipe necessary. I do not recall the name of the stuff he uses. Something for guns. He (Craig) may chime in if he reads this.

A far better solution is to send parts out for a black zinc plating. This as I recall is a chromate treatment to give it the color black similar to to the yellow gold. I think it lasts a lot longer and stays looking new.

[John D.]

Re: Black Phosphate

Richard, Eastwood: "Metal Blackener Solution" part#10113ZB.
Its pretty good stuff and is usuable over cadmium plating.
Here is how I use it on occasion (Typical I send parts off to my plater for blackening)
1st I dip the part is a mild solution of phospheric acid and water. Always wear eye goggles and unless your hands are leather like mine wear rubber gloves.
Rinse it off with cold water and pad dry.
Dip the part into the Eastwood solution and swish it around for about a minute or so.
Rinse it off with cold water. Dry it with a heat gun/hair dryer.
Then spray the part with the proper oil.
Directions on the bottle say it will not work with plated parts. But it does.!!!
Story: I ran out of #10 blackened split lock washers for my restos. Meanwhile while waiting for the order to come in I was in a bind here to get a job done.
So I took a small box of 100 split LWers and gave them the acid bath for a few seconds, rinsed them off, dried them with my heat gun, dipped them in a baby jar with a splash of Eastwood green blackener, let them soak for a minute, used my tea strainer to drain them, rinsed them off with cold water, dried them with the heat gun. Then I spread the little washers out on paper towels and sprayed them with 711 oil.
How job took about 5 minutes max. By the way the LWers were zinc plated when I started.

[Dick W.]

Re: Blach Phosphate

You can get Parkerizing, which is a very dark gray finish, solution from several of the gun web sites

[Gerard F.]

Re: Blach Phosphate

Richard,

To answer your original question, Zinc Phosphate is gray phosphate, not black phosphate. Depending upon the makeup of the the bare steel you are cooking with the zinc phosphate, and the amount of manganese in it, the part will come out a darker gray to black.

The truth is that black phosphate on bare steel was actually a mixture of zinc phosphate and manganese phosphate.

The Eastwood Zinc Blackener is actually a black oxide which turns Zinc or Cadmium Plating black, but without the grainy speckle finish in sunlight, that you would see with gray or black phosphate.

If you ever left a zinc plated part too long in Jasco Metal Etch (mainly phosphoric acid) and it came out black or gray, that's similar to black phosphate or oxide.

If you look at the second archived post down below, you 'll see where I replicated black phosphate by mixing zinc phosphate with black oxide (not Eastwood's), and cooking the raw zinc or bare steel part in a crockpot.

There is also a Restorer Story on this in the Winter 2006-07 issue.

I still keep a crockpot with the mix in it on my workbench. Whenever I want to do black phosphate, I just heat it up. For small part it just doesn't seem to wear out.

Have fun,

[Steve L.]

Re: Blach Phosphate

I've tried both Eastwood and Caswell "blackening". The Caswell is much better and you get a lot more of it. The reason I got both is that I got the Eastwood first. But it didn't last for a complete chassis rebuilt.

Either of them are not a good rest preventor, even with the sealer. I let them dry really well, then give them a quick spray of satin clear.

I bead blast first and immediately blacken them.

I've also tried Caswell black oxide over zinc parts. The black oxide is a bit shinier and a bit blacker. But could pass if you didn't look carefully at it.
I've tried this because some of the parts coming from vendors are zinc plated when they should be black phosphate. I hate removing the new zinc and then putting an inferior blackening on it.

[Mike Z.]

Re: Blach Phosphate

I agree the Eastwood product is decent. I use it when I am not too concerned of durability-the problem is, even with the oil treatment it will surface rust over time and look ugly again.

I have quit abit of cad plating done: the silver and gold dychromate. I ask my platter about black and there are a few options, of which I have been using black cad for sometime and very pleased with the result and durability (same as any cad). They also had the phosphate and a galvinized options-I did not like the finish as well (rough and more gray than black) and the phosphate will not have the durability.

Most cad platters have minimum job requirements (read cost), so cad plating a single part does not make sense, but if you are doing a complete car (nuts, bolts, backing plates, etc.) having the black done, starts to make sense-at least our local platter does not charge differently for the different colors within the same job order.

Mike Zamora
#12455

[Jeffrey S.]

Re: Blach Phosphate

The Caswell product is black oxide which is darker black and very even. I use that mainly for fasteners. I always remove the zinc plating first with muriatic acid and soak in a chemical rust remover like Evapo-rust. I have been using Shooters Solution black phosphate for hood latches, etc. which is grayer and has the sparkling texture. There have been many posts on these products giving the pros and cons of each. I think both are excellent products and highly recommend them.
Jeff